In order to filter, for example, in the automotive field, fluids such as fuels, operating media or passenger compartment air, often folded or pleated nonwoven filter materials are used. In this connection, it is often required to connect various edges or end sections of these flat filter materials with each other. Known filter elements are produced, for example, from initially zigzag-folded filter material sheets that are formed to a tubular body. In order to close the tubular body, the terminal fold sections must be connected with each other in a fluid-tight way.
In the past, for example, metal clips or clamps were used in order to hold the two flat sections resting on each other together. It is also conventional to adhesively connect the two filter material sheets with each other or to connect them by fusing. In particular in case of multi-layer filter media, for example, several layers of thin nonwoven material that is impregnated or comprises special intermediate layers, it is difficult to prevent fraying of the edges that are resting on each other. A particular difficultly resides in connecting the flat media to be connected fluid-tightly to each other, i.e., the fluid to be filtered may not pass unfiltered the filter material at the connecting location.